1. Field of the Invention
The present invention relates to a machine for the sorting by size of pear-shaped objects of the type comprising a conveyor, which is able to move essentially horizontally. The conveyor has a first alignment of equidistant parallel primary rollers separated each from the next by an interval allowing one object to pass through. The conveyor also has a second alignment of secondary rollers each arranged in alignment with an interval, which secondary rollers are able to move perpendicular to the plane of travel of the primary rollers. The machine has means to guide the secondary rollers along a sorting path of the conveyor, and the guide means being such as to progressively move the secondary rollers away from the primary rollers along the length of the sorting path.
2. Description of Related Art
Such a machine is disclosed for example in Patent Application FR-A-2 473 364. In that machine all of the primary and secondary rollers are rotated about their parallel axes.
Machines of the above type are used particularly for sorting generally spherical fruit or vegetables such as apples and oranges according to size.
The machine is not however suitable for pear-shaped fruit or vegetables, that is fruit or vegetables having the general shape of an oval with a more or less narrow end. Examples of fruits having this shape are pears, avocados and courgettes.
What is found is that the rotation of the rollers causes the objects being sorted to rotate themselves. The effect of the rotation, when applied to oval objects with a narrow end, is that the objects are caused to work their way towards one or other of the ends of the rollers. This migration of the objects along the length of the rollers injures them and crushes them, thereby impeding the normal operation of the machine.
It is an object of the invention to provide a machine for the sorting by size of pear-shaped objects that does not have the drawbacks mentioned above and which in particular prevents the transverse displacement of the objects during the sorting process.
To this end the subject of the invention is a machine for the sorting by size of pear-shaped objects, of the aforementioned type, characterized in that the primary and secondary rollers do not rotate about their axis for the greater part of the sorting path.
In accordance with certain particular embodiments, the machine has one or more of the following characteristics:
(1) the machine has means for positioning the objects with their longitudinal axis essentially parallel to the primary and secondary rollers;
(2) the positioning means comprise an auxiliary roller feeder whose rollers are rotated slowly about themselves and means of transfer from the auxiliary feeder to the conveyor with little or no modification to the orientation of the objects;
(3) the positioning means are built into the conveyor, the conveyor comprising, upstream of the sorting path, an object receiving section, along the length of which the primary and secondary rollers are rotated slowly about themselves in order to position the objects; and
(4) the machine comprises a plurality of elastically deformable adjacent revolving rollers located immediately beneath the sorting path in order to soften the fall of the objects.